HVAC GLOSSARY - U

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UA: A measure of the amount of heat that would be transferred through a given surface or enclosure (such as a building envelope) with a one-degree temperature difference between the two sides. The UA is calculated by multiplying the U-Value, or overall heat transfer coefficient U, by the area A of the surface (or surfaces).

Unconditioned Space: A space that is neither directly nor indirectly conditioned space, which can be isolated from conditioned space by partitions and/or closeable doors.

Upflow: (See Upflow Furnace).

Upflow Furnace: A furnace that pulls cool return air in from the bottom and blows/expels warm air out the top into the duct work. This type of furnace is usually installed in a basement or an out of-the-way closet.

Urea Formaldehyde Foam Insulation: (UFFI) A form of insulation no longer in use because of excessive formaldehyde emissions and documented associated health impacts.

Useful Thermal Output: The thermal energy made available for use in any industrial or commercial process, or used in any heating or cooling application, i.e., total thermal energy made available for processes and applications other than electrical generation.